Thermal spraying is a coating method wherein powder or other feedstock material is fed into a stream of heated gas produced by a plasmatron or by the combustion of fuel gases. The hot gas stream entrains the feedstock to which it transfers heat and momentum. The heated feedstock is further impacted onto a surface, where it adheres and solidifies, forming a thermally sprayed coating composed of thin layers or lamellae.
One common method of thermal spraying is plasma spraying. Plasma spraying is typically performed by a plasma torch or gun, which uses a plasma jet to heat or melt the feedstock before propelling it toward a desired surface. Most conventional plasma spray guns operate efficiently (e.g., over 60% efficiency) at one power mode (e.g., 75 kW) and in one position with respect to a specimen. Therefore, when spraying different surfaces and/or different specimens (e.g., at different power requirements), different plasma spray guns, arranged in different positions, may be necessary.